**Author details**

Yenizey M. Álvarez-Cisneros and Edith Ponce-Alquicira\*

\*Address all correspondence to: pae@xanum.uam.mx

Departamento de Biotecnología, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Mexico City, Mexico

### **References**

[1] World Health Organization. Global Action Plan on Antimicrobial Resistance. 2015. Available from: http://www.who.int/antimicrobial-resistance/publications/global-action-plan/ en/ [Accessed: Jun 26, 2018] ISBN: 9789241509763

[2] Antimicrobial Resistance in Food and Agriculture. FCC-EMPRES, information sheets. April 2017. Available from: http://www.fao.org/antimicrobial-resistance [Accessed: Jun 26, 2018]

in which the LAB is sensitive to the antibiotic analyzed is determined. The bacterium can be considered safe when the MIC is lower than the cutoff level (MIC < cutoff). On the other hand, if the MIC value is above the cutoff value (MIC > cutoff), the bacterium is considered resistant to the antibiotic, and its resistance should be confirmed by molecular methods as PCR [39, 54, 62]. However, the resistance genes not always are expressed but can be transferred to other bacteria if the environmental conditions stimulate the expression of these genes [34]. If the bacteria have intrinsic resistance, it is considered acceptable for use in food. Otherwise, it must be demonstrated whether the acquired resistance is in mobile genetic material or was acquired in the process of mutation in the bacterial chromosome (also acceptable for use in foods). Finally, the bacteria are not accepted by any regulatory body for its application in food

if it is demonstrated that the resistance is exogenous and easily transferable (**Figure 4**).

favor the resistance spread that threats the public health and the food production.

LAB are of great importance in the food industry for the preparation of fermented foods, in addition to being widely used as probiotics to regulate the intestinal microbiota in animals and humans. However, it is important to carry out the appropriate tests to identify the presence of antibiotic resistance genes that can be transferred horizontally to other microorganisms, whether pathogenic or those present in the gastrointestinal microbiota, which can cause a health problem because of the continuous exposure to the environmental conditions that

Departamento de Biotecnología, Universidad Autónoma Metropolitana, Unidad Iztapalapa,

[1] World Health Organization. Global Action Plan on Antimicrobial Resistance. 2015. Available from: http://www.who.int/antimicrobial-resistance/publications/global-action-plan/

**6. Conclusion**

68 Antimicrobial Resistance - A Global Threat

**Conflict of interest**

**Author details**

Mexico City, Mexico

**References**

"No conflict of interest declared."

Yenizey M. Álvarez-Cisneros and Edith Ponce-Alquicira\*

en/ [Accessed: Jun 26, 2018] ISBN: 9789241509763

\*Address all correspondence to: pae@xanum.uam.mx


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**Chapter 5**

**Provisional chapter**

**Development of Antibiotic Resistance in Wastewater**

**Development of Antibiotic Resistance in Wastewater** 

Antibiotic resistant bacteria and antibiotic resistance genes have been of the emerging contaminant threatening human health. The overuse of antibiotics, both in human patients and, importantly, in livestock, has led to an explosion of antibiotic-resistant bacteria, both in the U.S. and around the world. The prediction from the World Health Organization (WHO) is that, if nothing changes, the future will look a lot like the past where people die from minor injuries that become infected. One of the goals should be a long-term sustainable balance with everything in our environment, including bacteria to promote human health. Different microbial techniques have been employed to study the occurrence and spread of antibiotic resistance in the environment, preventing us from returning to a pre-antibiotic era. Dissemination of antibiotic resistance genes to the environment is an important factor causing an increased prevalence of resistant pathogens. Their spread to multidrug-resistant pathogens is one of the most emerging clinical

**Keywords:** antibiotic resistant genes, antibiotic resistant bacteria, wastewater,

Antibiotics have been used broadly in the last decades for disease control as well as livestock breeding. The misuse and inappropriate disposal of antibiotics can develop antibiotic resistance bacteria (ARB) and multi-drug resistant bacteria which carry one or more antibiotic resistance genes (ARGs). In this century, ARB and ARGs are known as emerging pollutants that threaten food safety and public health [1]. Antibiotic resistance has been identified as

wastewater treatment plant, microbial pathogens

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.81538

**Treatment Plants**

**Abstract**

challenges.

**1. Introduction**

**Treatment Plants**

Fateme Barancheshme and Mariya Munir

Fateme Barancheshme and Mariya Munir

http://dx.doi.org/10.5772/intechopen.81538

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

#### **Development of Antibiotic Resistance in Wastewater Treatment Plants Development of Antibiotic Resistance in Wastewater Treatment Plants**

DOI: 10.5772/intechopen.81538

Fateme Barancheshme and Mariya Munir Fateme Barancheshme and Mariya Munir

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.81538

#### **Abstract**

Antibiotic resistant bacteria and antibiotic resistance genes have been of the emerging contaminant threatening human health. The overuse of antibiotics, both in human patients and, importantly, in livestock, has led to an explosion of antibiotic-resistant bacteria, both in the U.S. and around the world. The prediction from the World Health Organization (WHO) is that, if nothing changes, the future will look a lot like the past where people die from minor injuries that become infected. One of the goals should be a long-term sustainable balance with everything in our environment, including bacteria to promote human health. Different microbial techniques have been employed to study the occurrence and spread of antibiotic resistance in the environment, preventing us from returning to a pre-antibiotic era. Dissemination of antibiotic resistance genes to the environment is an important factor causing an increased prevalence of resistant pathogens. Their spread to multidrug-resistant pathogens is one of the most emerging clinical challenges.

**Keywords:** antibiotic resistant genes, antibiotic resistant bacteria, wastewater, wastewater treatment plant, microbial pathogens

#### **1. Introduction**

Antibiotics have been used broadly in the last decades for disease control as well as livestock breeding. The misuse and inappropriate disposal of antibiotics can develop antibiotic resistance bacteria (ARB) and multi-drug resistant bacteria which carry one or more antibiotic resistance genes (ARGs). In this century, ARB and ARGs are known as emerging pollutants that threaten food safety and public health [1]. Antibiotic resistance has been identified as

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

a main public health concern by the World Health Organization [2, 3]. Antibiotics are most common strategy used in the treatment of bacterial infections, in addition, antibacterial metals are widely used to prevent bacterial attachment and to combat biofilms in hospital and food processing settings [2].

There is a report on the presence of 24 pharmaceuticals in 12 municipal and 4 livestock wastewater sludge showing that 17 and 14 pharmaceuticals were presented in municipal and livestock WWTPs, respectively. Nonsteroidal anti-inflammatory drugs were dominant in municipal WWTPs ranging from 0.42 to 367 mg/kg, whereas antibiotics (43.6 to 142 mg/kg) were dominant in livestock WWTPs [7]. The wide use of antibiotics in the livestock industry resulted in resistance of antibiotics to degradation that can lead to antibiotic resistance devel-

Development of Antibiotic Resistance in Wastewater Treatment Plants

http://dx.doi.org/10.5772/intechopen.81538

77

The concentration of 16 antibiotics was measured in sewage and activated sludge samples using high-performance liquid chromatography-tandem mass spectrometry [8]. Statistical analysis included general analysis (averages and standard errors), cluster analysis, and correlation and regression analysis (Pearson analysis). Their study found significant correlations between the relative abundance of ARGs and the corresponding residual antibiotic concentrations and heavy metals in the effluents of WWTPs and pre-treatment units for the antibiotics or metals are suggested. Further studies are essential to prove the causation of the results of

High concentration of antibiotics and their associated ARB and ARGs in the effluent of WWTPs enter the environment through WWTPs discharges to rivers, wastewater reuse, irrigation and amending the soil by biosolids make. Antibiotic resistance genes can persist in the environ-

Du et al. [9] studied ARGs including *tet(X), tet*(*W*), *tet(G), sul(1)*, and *intI(1)* in the influent and effluent of different units of a municipal WWTP. The studied plant possessed the anaerobic/ anoxic/aerobic membrane bioreactors (MBR). The decrease of ARGs in anaerobic and anoxic units followed by an increase of ARGs in aerobic units and then decline of ARGs in MBR units was reported in this study [9]. Anaerobic and anoxic treatments methods were more effective than aerobic treatment methods at removing ARGs. Because microorganisms have lower bioactivity under anaerobic condition and the propagation of resistance genes are inhibited [9]. Furthermore, a significant positive correlation was observed between ARGs and 16S rDNA in

Wang et al. [10] conducted a study to explore the concentration of five tetracyclines, four sulfonamides, and six fluoroquinolones in the rhizosphere soil that was irrigated by reclaimed wastewater for a long time. The total concentration of tetracycline was in the range of 12.7–

this study, soils that are irrigated by reclaimed wastewater accumulate antibiotics in several folds higher concentrations compared to the antibiotic concentration in the wastewater [10]. Wang and his research group studied soils of six public parks which were irrigated by the reclaimed wastewater. There was no antibiotic pressure but sulfonamide resistance genes (*sul(1)* and *sul(2)*) persisted in the soil. This result indicated that ARGs are more permanent

detected in soils and their highest total concentration was 79.2 μg kg−<sup>1</sup>

while no sulfonamide was found in samples. Fluoroquinolones were randomly

. Based on the results of

opment in the environment [7].

**2. Occurrence of antibiotic resistance in WWTPs**

ment even when there is no antibiotic pressure.

the wastewater treatment process [9].

this study [8].

145.2 μg kg−<sup>1</sup>

Antibiotics have been detected in sewage effluents, ground and surface water, sewage sludge, soil, and manure. Studies on the fate of antibiotics are motivated by two main concerns; first, antibiotics in the environment may contribute to the development of antibiotic resistant pathogens, second, the ecological consequences of antibiotic contamination that may enter in the human food chain. In a study conducted by Clarke and Smith on antibiotics in biosolids, norfloxacin, ofloxacin, ciprofloxacin, and doxycycline were measured in the sludge of a Swedish WWTP. Similar concentrations of ciprofloxacin and norfloxacin were also observed in sewage sludge samples from Switzerland. The concentration of these antibiotics was at the low mg kg−<sup>1</sup> dry weight range and was constant during the treatment processes. The same compounds and concentration were measured in soil that was amended by biosolids. Some of the compounds, for instance, carbamazepine and sulfamethazine can be translocated from the soil into the aerial plant components by uptake mechanisms in greenhouse plants [4].

Kim and Aga [5] studied the effects of antibiotics and ARB of wastewater treatment plants (WWTPs) on ecology and human health. Their study introduced the WWTPs as a point contamination source of persistent pharmaceuticals that affect the design and operation of treatment systems, antibiotic resistance development among pathogenic bacteria, and accumulation of persistent pharmaceuticals in soil and water. Their study estimated concentrations of antibiotics in untreated municipal wastewater in the United States and showed their possible metabolites in activated sludge [5]. They concluded that the disappearance of the parent pharmaceuticals in WWTPs does not certainly mean their complete removal. The presence of pharmaceuticals in the aquatic environment has ecotoxicological effects that impact the algal community structure and shifts the food web structure of streams [5]. The potential ecological and health impacts of antibiotics in the environment were investigated using environmental risk assessment including a two-stage process; estimation of expected introductory concentration (EIC) entering the environment and predicted environmental concentration (PEC). PEC is needed if the drug has the potential to bioaccumulate in the environment [5].

Determination and characterization of pharmaceutical compounds, antibiotics in particular, has attracted attention because of their ecotoxicological effects [5–7]. Antibiotics, such as tetracycline, sulfamethoxazole, ciprofloxacin, norfloxacin, trimethoprim, and ofloxacin, are determined in high concentration in the sludge of different WWTPs. In a study directed by Martin [6] sludge from four sludge stabilization treatments including anaerobic digestion, aerobic digestion, composting and the lagoon was monitored to detect the occurrence of 22 pharmaceutically active compounds. The average concentrations of studied compounds were 179, 310 and 142 μg/kg of sludge dry matter in primary sludge, secondary sludge, and mixed sludge, respectively. Sewage sludge that is used for the land application is always treated during one or more treatment processes namely, lime stabilization, thickening, dewatering, drying, anaerobic digestion or composting processes. However, many contaminants like antibiotic compounds may not be removed efficiently [6].

There is a report on the presence of 24 pharmaceuticals in 12 municipal and 4 livestock wastewater sludge showing that 17 and 14 pharmaceuticals were presented in municipal and livestock WWTPs, respectively. Nonsteroidal anti-inflammatory drugs were dominant in municipal WWTPs ranging from 0.42 to 367 mg/kg, whereas antibiotics (43.6 to 142 mg/kg) were dominant in livestock WWTPs [7]. The wide use of antibiotics in the livestock industry resulted in resistance of antibiotics to degradation that can lead to antibiotic resistance development in the environment [7].

The concentration of 16 antibiotics was measured in sewage and activated sludge samples using high-performance liquid chromatography-tandem mass spectrometry [8]. Statistical analysis included general analysis (averages and standard errors), cluster analysis, and correlation and regression analysis (Pearson analysis). Their study found significant correlations between the relative abundance of ARGs and the corresponding residual antibiotic concentrations and heavy metals in the effluents of WWTPs and pre-treatment units for the antibiotics or metals are suggested. Further studies are essential to prove the causation of the results of this study [8].
